• changzhu's avatar
    drm/amdgpu: add dummy read by engines for some GCVM status registers in gfx10 · a6522a5c
    changzhu authored
    The GRBM register interface is now capable of bursting 1 cycle per
    register wr->wr, wr->rd much faster than previous muticycle per
    transaction done interface.  This has caused a problem where
    status registers requiring HW to update have a 1 cycle delay, due
    to the register update having to go through GRBM.
    
    For cp ucode, it has realized dummy read in cp firmware.It covers
    the use of WAIT_REG_MEM operation 1 case only.So it needs to call
    gfx_v10_0_wait_reg_mem in gfx10. Besides it also needs to add warning to
    update firmware in case firmware is too old to have function to realize
    dummy read in cp firmware.
    
    For sdma ucode, it hasn't realized dummy read in sdma firmware. sdma is
    moved to gfxhub in gfx10. So it needs to add dummy read in driver
    between amdgpu_ring_emit_wreg and amdgpu_ring_emit_reg_wait for sdma_v5_0.
    Signed-off-by: default avatarchangzhu <Changfeng.Zhu@amd.com>
    Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
    Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
    a6522a5c
amdgpu_gfx.h 11.3 KB